Draught regulator



Juy x9,v 1935. F. I QTR'ETHEWEY 2,997,486

DRAUGHT REGULATOR Filed March' 12, 1934 u b k, g h la Q- E n i 7-@ f E] Vv 0 S i f l INVENTDR mg jij x .4 p

.FLTTY Patented July 9, 1935 UNITED rSTATES Y DRAUGHT REGULATOR Frank L. Trethewey, Toronto, Ontario, Canada Application March 12, 19,34, Serial No. 715,040

8 Claims.

of the iiue gases from the furnace, which will-be very sensitive, which will have a wide range, which Will be durable and efficient and which will be responsive to varying outside temperatures.

I attain my object by means which may be brieiiy described as follows. A thermostatic element is positioned in a ilue through which pass the products of combustion from the furnace. With this flue at the furnace side of thev thermostatic element communicates an inlet for atmospheric air which is provided With'a damper controlled by said element. Thus, when the damper is partly or wholly open, the thermostatic element is exposed to a mixture of the flue gases and cooler atmospheric air, which mixture is subject toV much greater' changes of temperature than the flue .gases themselves, so that the movements of thethermostatic element are much greater than if it were affected by the flue gases alone and more accurate regulation of theV damper results. A second damper is preferably positioned in the ue between the air inlet and the furnace which is actuated by the thermostatic element simultaneously with the irst mentioneddamper. The inlet for atmospheric air is optionally piped to communicate with the air outside the building. Thus the draught control is made responsive to the load imposed on the heater by temperature of the outside air, or inside air as the case may be, accordingas room air or'outside air is acting on the thermostatic element. V y s Further features of the invention will hereinafter appear and the whole is hereinafter more fully described and is illustrated in the accompanying drawing in which Fig. 1 is a side elevation of mydraught regulator,

Ipartly broken away;

Fig. 2 a plan View of the same; and y Fig.V 3 a longitudinal sectional detail of the thermostatic element and its mounting.

In the drawing like numerals ofreference indicate corresponding parts in the different figures.

Referring to the drawing, I is a smoke flue, which is shown as a pipe adapted to be connected with'thesmoke outlet of a stove or furnace. In the side of this ue is an opening 3 with which communicates an air ue 2. This air vflue communicates with the atmospheric in the chamber in which the heater'is located, but may, of course,

be extended` to communicate with the outside air.

Y The passage of air through the opening v3 is Acontrolled by means of the butterfly damper 4, which is secured to a spindle 5 journalled in the walls of the flue.' This damper thus controls the admissionlof cold air to the interior of the iue i. Within the flue I at that side of the opening 3 which is nearest the heater with which the flue I is connected is positioned the butterfly damper 10 i5 which is connected to the spindle l journalled in thewalls of theue.

`The spindle 5 is-provided with the crank arm 8 and the spindle ,'I with the crank arm 9. To thesegcrank arms is pivotally connected the con- 15 necting rod 'I6 so that the dampers may be actuated simultaneously.

In the full draught position it will be noted that the damper will be positioned longitudinally of the iiue I and the damper 4 transversely ofthe 20 iue 2, while in the minimum draught position the position of these dampers is reversed.

The dampers are actuated by a thermostatic element which is positioned in the ilue I at that side of the opening 3 which is remote from the 25 heater with which the ue I is connected. Thus the thermostat will be exposed not only to the heated flue gases, but also to the effect of cold air admitted through the opening 3. Y

The thermostatic element comprises a support- 30 ing member I I, which is secured to the side of the flue by means of Ythe bolts I2. This Vsupporting member closes an opening in the side of the flue I l which is of a size adequate for the passage of the parts of the thermostatic element which are re- 35 quired to be positioned within the iiue. In they supporting member is journalled an anchor member I3 and Within the anchor member is journalled the spindle Ill. A thermostatic coil I5 of the usual loi-.metallic type has one end secured 40 to the spindle and the other end securedY to the anchor member. If the anchor member be held from rotatingthen the expansion and contraction of thethermostatic coil will rotate the spindle I4.

To the outer end of the spindle I4 is secured or `45 formed the crank arm I8, which crank arm is pivotally connected to one end of the connecting rod 23, the other end of which is pivotally connected with the crank arm 9 of the spindle 'I of the damper 5. Simultaneous operation of the dampers YIl and 5 is thus obtained from the one thermostatic element.

The anchor member I3 is rotatably adjustable so that the thermostatic element may be set to causeit to move-the dampers to the. substantially no draught position at a predetermined temperature of the gases to which the thermostatic element is subjected. For this purpose I provide the anchor member with the hand wheel I 6 by means of which it is rotated. Preferably the anchor member is held in the position to which it is adjusted by frictional rather than positive means, and for this purpose I provide the brake plunger 2D slidable in the supporting member I I and engaging the anchor member.

The outer end of the plunger is slidable in the pointer I1, which serves as an indicator to show the setting of the anchor member. A coil spring 2| bears against the pointer and against an abutment pin 22 passed through the plunger 20. The

friction of the plunger is sufficient to hold the outer member stationary in any position to which it has been turned, while the anchor member may slip to avoid straining of the thermostatic coil if the latter be overheated. 'I'he end of the plunger fits into a groove in the anchor member and thus holds it from endwise displacement.

The mode of operation is as follows. With a coldfiue thedampers will be in such a position that'themaxirnum desired opening of thelue I and the minimum desired opening of the flue 2 is obtained. Whenua re is made up in the heater the y flue gases become warm and the thermostatic element then operates to move the dampers to check the draft. This immediately admits more c old air to mix with the flue gases and thus cools the thermostat and prevents an undue choking `down of the draught. If the fire remains vsteady the'apparatus soon attains a position of air the device is sensitive to outside air conditions and draughtis increased as outside temperatures fall and vice Versa.

The maximum temperature necessary in the mixture of air andwfiue gases impinging on the thermostatic coil `before the dampers will be moved to the full checkvposition is regulated by adjusting the anchor member. The dampers are Y stopped from passing the full draught position by the engagement of the end I 9 of the crank arm I8 with the underside of the connecting rod I0 which avoids the usey of stops within the nues.

It will be noted also that the thermostatic ele- `ment is readily removable for cleaning by lifting the plunger-w20 and withdrawing the velement through the opening in the supporting member.

While the thermostatic element preferred is of kthe type shown it will be understood that other known forms might be substituted in broad embodiments of the invention.

From the above description it will be seen that I have devised an automatic draught control which will satisfactorily attain the objects of my invention Yas hereinbefore set forth.

What I claim as my invention is:

1.`In an automatic damper, the combination with a iiue having an inlet for atmospheric air, of a thermostatic element positioned in the flue in the path of ilue gases and of air entering the opening in'the flue under the iniiuence of nue gases travelling through the flue comprising a thermostatic coil, a spindle passing through the fluewall and to which one end of the coil is secured, and an anchor member carried by the flue .Wall and to which the other end of the coil is secured; means for rotatably adjusting the anchor member; a crank-arm on the spindle; a pivoted damper; a crank arm connected with the damper; and a connecting rod pivotally connected with the crank arms.

2. In an automatic damper, the combination with a flue having an inlet for atmospheric air, of a thermostatic element positioned in the flue in the path of ue gases and of air entering the opening in the iiue under the inuence of flue gases travelling through the flue comprising a thermostatic coil, a spindle passing through the flue wall and to which one end of the coil is secured, and an anchor member carried by the ilue wall and to which the other end of the coil is secured; a crank arm on the spindle; a damper pivoted in the air opening; a crank arm connected with said damper; a damper pivoted in the iiue; a crank arm connected with said damper; a connecting rod pivotally connecting the damper crank arm; and a connecting rod pivotally connected with the crank arm of one damper and the crank arm on the spindle.

3. In van automatic damper, the combination with a iiue having an inlet for atmosphericair, of a thermostatic element positioned in the iiue in the path of iiue gases and of air entering the opening in the ue under the iniiuence of iiue gases travelling through the flue comprising a thermcstatic coil, a spindle passing through the flue wall and to which one end of the coil is secured, and an anchor member carried by the flue wall and to which the other end of the coil is secured; a friction brake yieldingly resisting the rotation of the anchor member; a crank arm on the spindle; a pivoted damper; a crank arm connected with the damper; and a connecting rod .1.

pivotally connected vwith the crank arms.

V4. In an automatic damper, the combination with a Viiue having an inlet for atmospheric air, of`a thermostatic element positioned in the flue in the'path of ilue gases and of air entering the opening inthe flue under the influence of flue gases travelling through the flue comprising a thermostatic'coil, a spindle passing through the ilue wall and to which one 'end of the coil is secured, and an anchor member carried by the flue wall and to which the other end of the coil is secured; a crank arm on the spindle; a damper pivoted in the 'air opening; a crank arm connected with said damper; a damper pivoted in the flue;

a crank arm connected with said damper; a conl.

necting rod pivotally connecting the damper crank arm; aconnecting rod pivotally connected to the crank arm' on 'the spindle and the crank arm of the flue damper; and a projecting part on the spindle crank arm engageable with the connecting rod aforesaid to form a stop defining the full draft position of ther dampers.

5.V In an automaticV damper, the combination with communicating flues each'having a damper therein; crank arms connected respectively with the dampers; a thermostatic'element in one Vflue; a spindle journalled in the last mentioned flue operable by the said element; a crank arm on the spindle; a connecting rod pivotally connected with the crank arms of the dampers; and a connecting rod pivotally connected with the spindle crank arm and one of the damper crank arms.

6. In an automatic damper, the combination with a flue having an opening therein for the passageY of a thermostatic element; a supporting,

member for a thermostatic element detachably secured to the flue Wall aboutsaid opening; and a thermostatic element comprising a thermostatic coil locatedin the flue, an anchor member journalledin the supporting member, a spindle journalled in the anchor member, and means for rotatively adjusting the anchor member relative to the supporting member, the coil being secured at opposite ends to the spindle and anchor member; and a damper operable by the spindle.

7. In an automatic damper, the combination with a flue having an opening therein for the passage of a thermostatic element; a supporting member for a thermostatic element detachably secured to thev flue Wall about said opening; a thermostatic element comprising a thermostatic coil located in the flue, an anchor member journalled in the supporting member, a spindle journalled in the anchor member, and a friction brake yieldingly resisting relative movement of the anchor member relative to the supporting member,

the coil being secured at opposite ends to the spindle and anchor member; and a damper operable by the spindle.

8. In an automatic damper, the combination with a flue having an opening therein for the passage of a thermostatic element; a supporting member for a thermostatic element detachably secured to the iiue yWall about said opening; a thermostatic element comprising a thermostatic coil located in the flue, an anchor member closing the opening aforesaid and releasably held therein, a spindle journalled in the anchor member, the coil being secured at opposite ends to the spindle and anchor member; and a damper operable by the spindle.

FRANK L. TRETI-IEWEY. 

